The present invention is generally related to wireless communications, and more particularly to the use of an amplification system to improve the range of reception of a transmitted signal, by improving the receiver sensitivity.
Wireless communications systems are well known in the art. In wireless communications systems such as a cellular telephone system, wireless signals are transmitted from a base station to a cellular handset, and from the cellular handset to the base station. The base station and the cellular handset each contain circuitry that allows them to receive the signals transmitted by their system counterpart and to decode data that has been encoded into the transmitted signal.
Typically, a cellular system will include one or more service cells, where each cell has a base station that provides telecommunications services to cellular handsets within the service area. The size of the base station cell will be a function of the range over which the base station may transmit radio signals that may be received by the cellular handsets, and also is a function of the range over which the base station may receive a signal that has been transmitted by a cellular handset. Base stations are generally not power limited, and may amplify signals as required in order to decode data that has been encoded for transmission from the cellular handsets. In contrast, cellular handsets typically are power limited, and can only achieve a limited signal-to-noise ratio without using power at a rate that would be commercially unacceptable.
This constraint on the power requirements for cellular handsets tends to limit the size of the service cell for a base station. This limited size of the service cell in turn requires that an increased number of base stations must be provided in order to provide wireless communications services in the cellular system. Increasing the number of base stations for a cellular system results in significantly increased costs for real estate and equipment. Cellular system operators utilize suitable known methods to help minimize such costs, such as by increasing cell size. Regardless of the known interest in increasing cell size, extremely low-noise amplification of cellular signals at the handset typically results in power losses that are unacceptable, regardless of any potential increase in cell size that may be realized by amplification of such signals.
Therefore a system and method for amplifying a transmitted signal are required that overcome the known problems and deficiencies of existing systems and methods for amplifying transmitted signals.
In particular, a system and method for amplifying a signal are required that maximize the benefits of amplification while minimizing the power requirements that are required for amplification.
In accordance with the present invention, a system for amplifying a transmitted signal is provided. The system includes a receiver that receives the transmitted signal. A non-linear oscillator, such as a synchronous oscillator that is operating in a borderline stable condition, is connected to the receiver. The non-linear oscillator receives the transmitted signal from the receiver and amplifies the transmitted signal without modifying the phase or frequency of the transmitted signal.
The present invention provides many important technical advantages. One important technical advantage of the present invention is a low-power system for amplifying a transmitted signal that increases the signal relative to the noise. The system of the present invention thus allows transmitted signals that carry data that has been encoded by phase or frequency modulation to be received over a greater service area, without regard to the fact that the amplitude of the signal is not being amplified in a linear fashion.
Present invention also provides a method that allows the service area of a service cell to be significantly increased without a proportionate increase in power required for amplifying transmitted signals. The present invention thus decreases costs for cellular systems by increasing service areas of cells, but does not result in adverse power losses and shortened battery life for cellular handsets.